Tensioning device for a web in a slitting apparatus



July 31, 1962 J. E. COLE 3,046,823

TENSIONING DEVICE FOR A WEB IN A SLIT'I'ING APPARATUS Filed Oct. 4, 1957 2 Sheets-Sheet 1 ENTOR JAM E. COLE July 31, 1962 Filed 001:. 4, 1957 FIG. 3

FIG. 2

J. E. COLE 3,046,823

TENSIONING DEVICE FOR A WEB IN A SLITTING APPARATUS 2 Sheets-Sheet 2 ATTQRN Y5 3,046,323 'I'ENSIONING DEVICE FOR A WEB DI A SLITTING APPARATUS tats tet James E. Cole, Alpha, Ni, assignor to Riegel Paper The present invention relates to web slitting apparatus, and more particularly to specific improvements in apparatus for continuously slitting elongated webs, of flexible material, such as paper, for example.

In the processing of certain web materials, such as paper, it is often expedient to pass an elongated web section longitudinally through a slitting device, whereby the web is severed continuously into a plurality of elongated strips. A conventional apparatus for this purpose is a Fales type slitter, for example, which comprises one or more cooperating pairs of slitting knives arranged in overlapping relation and adapted to rotate about axes disposed transversely of a web, on opposite sides thereof. As the web is drawn longitudinally between the pairs of rotating knives, the knives continuously shear the web into longitudinal strips.

In many slitting operations, it is desirable or expedient to slit a relatively wide web of material to form a large number of narrow strips. In such cases, the slitting apparatus comprises a relatively large plurality of pairs of slitting knives mounted on shafts disposed on opposite sides of the web. While these conventional arrangements are suitable for many operations, it has been found, in connection with the slitting of material such as paper, that it is difiicult if not impossible to maintain substantial accuracy in the width of the cut strips. Thus, it has been observed that as the web of material approaches and passes between the cooperating sets of slitting knives, the, eccentric shearing forces applied to the web cause the web to wrinkle between the sets of cutters and the width of the cut strips is found to be slightly greater than the spacing between axially adjacent sets of slitting knives. The discrepancy in Width may be of considerable importance where the overall width of the strips is rela tively small, and the behavior of the web is often such that the width varies from point to point, providing an unsatisfactory endproduct.

In accordance with the invention, a slitting device of an otherwise conventional design is provided with an improved arrangement for handling the web immediately prior to the passing thereof between the sets of slitting knives, whereby the web is maintained in a substantially flat condition throughout, and the outstrips are of uniform, accurately predetermined width throughout. More specifically, the'inventio'n' provides a novel and simplified arrangement whereby as the web approaches the slitting knives it is pressed'flat'upon' a'supporting plate at predetermined points, and placed under a slightly increased tension at such points. The arrangement is such that the tendency of the 'web towrinkle or form waves between the pairs of slittingknives' is substantially or wholly eliminated, and the several longitudinal elements of the web, which eventually form the cut strips, are maintained in a fiat condition as they pass between the respective sets of slitting knives.

In a preferred form of the invention, a slitting device of otherwise conventional design is provided with a plurality of pressure members which press the web downwardly onto a supporting plate, immediately adjacent the entry side of the slitting knives, a pressure member being provided for each of the theoretical longitudinal elements of the web which is eventually formed into a cut strip. By this means, each longitudinal element of the web is pressed flat and placed under a slightlyincreased tension over an area within, but not extending to the lateral limits of the element. Each element is to be maintained in a fiat, taut condition as it passes through the slitting knives, so that slit strips are accurately formed to the desired widths. i For a better understanding of the invention, reference should be made to the description and the accompanying drawings, in which:

FIG. 1 is a fragmentary perspective view, partly in section, of a slitting apparatus incorporating the improved features of the invention;

FIG. 2 is a fragmentary cross-sectional view of the apparatus of FIG. 1; and I FIG. 3 is a fragmentary and elevation, as taken along the line 3-3 of FIG. 2.

Referring now to the drawing, the numeral 10 designates generally the frame of a slitting apparatus, the frame mounting a pair of guide rollers 11, 12 and a pair of slitter shafts 13, 14. A web 15 of material, coming from a siutable source thereof (not shown) is passed around the guide rollers 11, 12', in that order, and is then passed between the slitter shafts 13, 14, after which it is taken to suitable wind-up means W (FIG. 2) which take up the strips in coil form as indicated at C.

In accordance with usual practice, the slitter shafts 13, 14 are disposed transversely of the web 15, in parallel relation thereto, and are journaled in the frame 10 for rotation. The shafts 13, 14 are adapted to receive a plurality of slitting knives 16 and spacing collars 17, the collars 17 being inserted between adjacent slitting knives to space the knives a predetermined fixed distance apart. As shown in FIG. 3, the knives and collars 16, 17, on the respective shafts 13, 14, are so arranged that the corresponding knives on the respective shafts are placed immediately adjacent each other, in overlapping relation, so that pairs of slitting knives are in shearing relation. Accordingly, when the web- 15 is passed between the slitting shafts 13, 14, the cooperating pairs of slitting knives 16 are effective to sever the web longitudinally in a continuous manner. As a general rule, the slitting shafts 13, 14 are power driven to facilitate the cutting action of the overlapping knives.

As shown in FIG. 1, as the web 15 passes between the slitting shafts 13, 14, the web is severed into a plurality of separate strips 15, depending upon the number and position of the pairs of slitting knives. Ideally, the width of the slit strips 15' should be exactly equal to the spacing between the sets of slitting knives. However, under normal conditions it has been found that the web tends to buckle or wrinkle between and rearwardly of the sets of the slitting knives and the Width of the cut strip 15' is thus somewhat greater than the spacing between slitting knives. That is, the longitudinal elements of the web 15, which eventually become the separate slit strips 15, tend to buckle transversely of the web prior to passing through the slitters, so that the width of such longitudinal element, as it is cut, is greater than is desired. v

In accordance with the present invention, buckling of the longitudinal elements of the web is avoided by provid ing a plurality of pressure members, generally designated by the numeral 18, which act upon the longitudinal elements of the web and press the elements against a supporting plate 19 mounted on the frame It Advantageously, the pressure members 18 are positioned adjacent the entry side of the slitting knives 15 and are aligned with individual slit strips 15, a pressure member being provided for each-of the slit strips. In the illustrated apparatus, the active surface portions of the pressure members are of slightly less width than that of the strips 15 and 3 are substantially centered with respect to the lateral edges of the slit strips, whereby the pressure members act upon longitudinal elements of the web, such as indicated at 15a, 15b, over acentral portion thereof.

porting bar 25 positioned over and disposed transversely of the web 15. .The clamps 23 extend around'the bottom of the supporting bar 25, and the respective pressure members 13 may be individually clamped to the bar 25. The arrangement is such that the pressure members 18 may be adjusted individually along the supporting bar 25, as well as rotated into desired positions with respect to the supporting plate 19, whereby proper alignment with and pressure upon the longitudinal elements 15a, 15b, etc. of the web may be obtained.

' As shown in FIG. 3, the individuallpressure members 18 are advantageously so adjusted as to be centrally aligned between adjacent cooperating pairs of slitting knives 16. It will also be observed in FIG. 3 that the Width of the pressure foot 20 of eachpressure member is slightly less than the'spacing between the adjacent sets of knives.' By way of example, and not of limitation, the pressure feet 20 may have a Width of approximately 2 /2 inches, where the spacing between adjacent sects-of slitting knives is approximately 3 inches. 7

When the pressure members 18 are properly adjusted, each member will be substantially centrally "positioned with respect to one of the theoretical longitudinal elementslSa, 15b, etc., of the web, and the pressure feet 20 of the members 18 will press lightly upon the web, urging it into fiat relation to the plate 19. As will be noted in FIG. 2, the pressure feet 20 act upon the web '15 slightlyfin advance of the slitting shafts 13and 14. By

way of example, the pressure feet 20 may be located in the order of inches in advance of the shafts 13, 14.

With the pressure members 18 thus properly adjusted, the web 15 may be passed through the slitting device and severed into a plurality of separate strips 15' of relatively narrow width, with the width of the slit strips accurately V reflecting the predetermined spacing between axially ad-- Y jacent pairs of slitting knives.

The apparatus of the invention is particularly advantageous in connection with the slitting of a relatively wide paper Web into a plurality of strips of relatively nar-' row width. Heretofore it has been difiicult, if not impossible, to accurately regulate the width of the slit strips due to the tendency of the web to buckle and form Waves while-passing'between the slitting knives. Moreover,

such variations in width'were not always consistent and predictable in that the buckling of the web elements may vary ii magnitude from point to point along the web.

The improved form of slitting apparatus is realized by providing a generally simplified and economically manufactured attachment for an otherwise conventional slitting device. The attachment is readily adjustable to accommodate most commercial slitting operations, regardless of the number or size of the slit strips, since the pressure members 18 may be of various sizes, and are individually adjustable on the supporting bar 25.

representative only, as certain changes may be made therein without departing from the clear teaching of the invention. Accordingly, reference shouldbe made to the following appended claim in determining the full scope of the invention. a

.Iclaim: I v.

In combination with a web slitting device for slitting paper webs, said slitter being of the type having ,a plurality of pairs of cooperating disc-typeslitting knives ar:

ranged in pairs in overlapping relation for continuously severing a paper web drawn longitudinally past the knives into a plurality of separate strips, a rigid and fixed continuous web supporting plate disposed horizontal-1y positioned adjacent the entryside of said slitting knives for continuously supporting the web across its. entire width as the web moves toward the knives, a rigid and fixed supporting rod positioned over said plate and extending across the width of said web, a Z-shaped pressure member for each of said separate strips, each'of said pressure members'having a depending portionand:

a cantilever-supported pressure-foot extending horizon-' tally forward from said depending portion, each of said pressure members further having a clamping arm extend-- ing rearward toward and. adjusta'bly mounted on said,

supporting rod for adjustably securing the pressure mem-. 1

her to the rod, each of said pressure members being formed of strip like material for accommodation offlex- 7 ing of the pressure foot thereof in accordance'with: adjustments of the pressure member on said rod, saidpres sure members being slidablyand rotata'bly adjustable on said rod, freely accessible means on the clamping arm of each pressure member for independently releasably securing each of thepressure members in predetermined adjusted position on said rod, said pressure members being positioned adjacent the entry side of said slitting knives with their pressure feet slidably engaging portions of the Web passingforwardly over said plate andpress:

ing said portions of the web against the fixed plateto longitudinally tensiontlie web, said pressure members 1 being of a width slightly less thanthe'spa'cing between' adjacent sets of slitting knives and being arranged such f that apres s'ure member is positioned in alignment be tweeneach'set of two pairs of slitting knives, each of said pressure. members being further arranged'with its pressure fo'ot pressingupon 'a separate area of said web to individually tension a'separate longitudinal strip area of the web, which ultimately becomes aseparate slit strip, and wind-up means on-the exit side of the slitting knives for drawing theweb past the knives. 1

I References Cited in the file of this patent j V 1 UNrrnD STATES PATENTS V Beaumont Nov. 6, 1883 299,982 Hodgson a June-.10, 1884 673,473 Peu'ckert 'May-7, 1901 901,126 'S-chaefer .Oct. 13, 1908 1,067,269 Palmer .i.. July 15, 1913 1,164,650 Ireland Dec.'21,191 5 1,200,136 Richardson' Oct. 3, 1916 1,517,081 Loh-r o NOV. 25, 1924 1,827,193 I Fischer et .al. j Oct. 13, 1931 2,204,904- Moore June 18, 1940' 2,533,996 Clarkson Dec..12,'1950 V FOREIGN PATENTS 132,735,

Germany July 15, 1902 

